Complex compounds of tetraisopropyl zirconate with ammonia



ammonia complex.

Kendall Company, Boston, Mass., a corporation of Massachusetts Y No lirawing. Filed'-Oct.'23 ,-i95 8, Ser. No; 769,699

seams: e1; 260429.

This invention relates is; competes er" ietraiseprspyi zirconate and ammonia and pertains more s'p'ecifical y to such complexes containing up to' two moles of ammonia per mole of zireonate; f

Tetraisopropyl zirconate", as is well known, is useful as' a catalyst'for estefeifiterchangeflreactions" and'is also customarily employedasthestafiing mate ial in the preparation of'otlier fetr'aiallyl'zirconates', The tetfais'opropylzirconate is jcemmsniy pared byre'actingzifcloniurh tetrachloride with iisepre yi alcohol, then introucisgsnhydiotrs anir'iio ia to neutralize the liberated hydrochloric acid, naemia chloride being precipitated and retrieved by filtration. The desired grease is 65 tained by distilling the reaction 'mrxmreartegr val of the ammonium chloride, but the procedureleads to very ear" yields, thepro reinstating to any i0% is 15% of thet'hecrctical yield The product is extremely sitsceptible to hydrolysis appreciable decomposition ccur: ring' as soon as it is exp osd to the atmosphere. It has been proposed to employ; instead'of tetraisopropyl zirconate, the complex of this compound with onemolecule of t'eti'aisbp'ropyl alcohol, and it has been found that such a complex can be obtained in ayield of a'pprpximately. 50% to 60% of the theoretical whenthe above-described reaction is carried outin the presence of'e'xc'ess alcohol. However, the alcohol complex is also extremely susceptible to hydrolysis and begins to decompose when exposed-to-theatrnosphere "foras little as a fraction of a minute. Accordingly,the cgrnplex, like the tetraisopropyl zirconate, is extremely difficult to handle;

' special precautions are required to carry out even such V complex in pure form by simply heating at reduced pressure at a temperature of l00-120 C., the amount of tetraisopropyl zi'rconate obtained by this procedure amounting to upwards of 70%"of the theoretical amount based on. the amount of zirconium tetrachloride starting material and over 97% ofthe: theoretical based on the While one ofthe complexes of the present invention containing two moles of ammonia for each mole of zirconate (a: -diammoniate i-s obtainable in high yield, is J resistant to hydrolysis, and canreadily be heat-decomposed to provide tetraisopropyl zirconate in substantially v theoretical yield, this complex is relatively unstable, rapidly losing the first of its two molecules'of ammonia when v nitecl States Patent ingv only one mole of ammonia for each mole of zirconiurn (a. mane-manner ont he other hand, possesses the" advantage not only of providing a high yield of tetraisopropyl zirconate, but is itself relatively stable so far as loss of ammonia is concerned and undergoes little or no physical disintegration upon exposure to the atmosphere at room temperature". Consequently, this monoammoniate is much less susceptible to hydrolysis than the diammoniate and is also very much less susceptible to hydrolysis than is the alcohol complex referred to above. As a consequence of its stability, it may be weighed on a conventional balance without any special precautions with a high degree of accuracy, in contrast to the special precautions required with the alcoholate. It is very stable when stored in closed coritainersat temperatures below 0 C., no' apparent change in composition occurring. even after periods of several weeks. This complex is therefore the material of choice.

, Wlien stored in closed containers at temperatures from 0 to +10" C., the complex described above slowly loses a fraction of its ammonia content. When the ammonia content reaches 0.8 mole per mole of zirconate, however, the complex ieinains stable in storage under these conditions. 7

Storage at room temperature protected from the atmospnere iii a closed" container leads tofurther loss of ammonia. the complex at this temperature apparently being stable when it has an ammonia content of 0.5 mole per mole of zirconate, Complexes containing from 0.5 to 1.0 mole of ammonia per mole ofzirconate are preferred for most purposes.

The following. specific examples will serve to illustrate the nature of theinvention moreclearly without acting as a limitation upon the scope thereof.

Example 1' 'jl herewas introduced into a carefully dried flask provided with a condenser 1-69 g of anhydrous zirconium tetrachloride and 1500 ml. of anhydrous isopropanol, takingcar eful precautions to avoid contact of either of the" -reagents' with the atmosphere in order to prevent possible;hydrolysis.- The flask ,was protected fromthe atmosphere with an absorption tube containing calcium exposedto the atmosphere and bre'a'king-down' physically toextremely small particles.

. i "these particles then facilitates relatively ra'pid hydrolysis:

- of the materialexposed to the atmosphere. Furthermore,

a. this complexiisj only slightly soluble at room -tempera- 7 lturefnsolvents such-as alcohols-3 The complex contain The large surface area of I additional dry ammonia.

hydride. The excess alcohol above the four moles required for each mole of zirconium tetrachloride served as a solvent and diluent. After standing overnight at room temperature, dry ammonia was bubbled into the reaction mixture at the rate of l /zto 2% liters per minute while stirring mechanically, leading to the precipitation of ammonium chloride. Introduction of ammonia was continued until the system was alkaline to litmus. The solid precipitate of ammonium chloride was removed by filtration and the filtrate was cooled to a temperature of --l0 to -20 C. while introducing Large colorless crystals soon appeared which could readily be separated by fitration.

The crystals, which upon analysis by weight loss were found to contain 9.1% ammonia (calculated 9.4% ammonia for the diammoniate), had the formula the weight of the zirconium tetrachloride.

.'Ihe crystalsof the diammoniate were found to be eflluorescent in air, rapidly falling apart to a powder which then quickly hydrolyzed in, contact with the at-' mosphere. Tetraisopropyl zirconate of high purity could I readily be obtained simply by heating the crystalsa' reduced pressure'at a tempreature of 1105- C. ffThe" tetraisopropyl airconate thus produced waslof very high j Patented Mar. 28, 1961 purity, as shown by the fact that when distilled at reduced pressure it left substantially no residue.

Example 2 A mixture of 169' g. of anhydrou' szirc onium tietrg-i chloride with 1 liters of.anhydrous isopropylalcohol was placed in a flask provided with a condenser, flboth flask andcondense'r being carefully dried, and-provided with an absorption tube containing calcium hydride to ensure protection of the reaction mixture from atmos pheric moisture. After standing overnight, dry ammonia was introduced into the flask at the rate of 1% 'to' 2' /ij litersper minute while heating the mixture at reflux five hours, during whichjtimei ammonium chloride precipitated. I 1 The reaction mixture was; then filtered to'remove'the ammonium chloridewith'precautions to 'avoidfcontactfof.

the" mixture with the, atmosphere. Additional 'dry am-, monia was then introduced intothefiltrate while the latter was maintained at. 40"C., the ammonia being introduced at the rate" of 1% to 2% liters perminute for thirty minutes; After storage of the mixture-at '0 C. overnight, large colorless crystals formed which could readily be separated by filtration,.and additional crystals were obtained by evaporating oil. the solventwhile intro; ducing further ammonia followed by "cooling.

=68.8%;.calculated for zr=2 6.s%, NH ==4.95%, -tetraisopropoxy,=68.6%.

- The crystals could be exposed to the atmosphere'for as much as 20 to 25 minutes at room temperature before J exhibiting any evidence a c i -substantial hydrolysis.

' Analysis of a sample of the'pr'oduct after storage in a closed bottle at to 0 ,C. fora period of several days showed no change in composition. A second sample storedin a closed bottle at 0 to-L- IO? C."1ost a'siibstanf tialfportion of its ammonia content ovcrnightfthe 'am monia content-then being determined .to' be 4.10%; After a months further storage under the same conditions; no further change in composition occurred, indicatingthat under these, conditions the; ammoniate containing The crystals were a z and found to have the following composition: Z r=27,00%, him-=431%,.teuaiwpmmxy "as-mare.

approximately 0.8 mole of ammonia per conate is stable.

Another sample was stored in a closed bottle at room temperature overnight, whereupon the ammonia content wasrfo und to have dropped to 2.5%. Further storage under the same conditions if or a period of a month produced no further change in composition. The form of mole of ziramr'noniate'stable under these conditions therefore contemperature (82"C.) with constant stirring. Theintroduction of ammonia wascontinued for approximately of ammonia per mole of zirconate.

"Example fl 'A sample of the complex prepared in" Example 2 containing one mole of ammonia per moleof zirconate was placedin a flask and the flask was evacuated to a pressure of 1 to 2 mm. The flaslg'was then placed in a heating bath maintained at a temperature of 120 C., whereupon rapid evolution of ammonia from the sample occurred.

tains about 0.5 mole ,After three minutes no further gaswas evolved, and the productwa's' in the form of a clear limpid liquid which upon. analysis' showed a zirconium content of 28.02% (calculated for tetraisopropyl zirconate, 27.84%). The liquid tetraisopropyl zirconate thus prepared could be distilled substantially completely, leaving almost no resij due. This isin striking contrast to the behavior of tetraisopropyl zirconateprepared by other methods which leaves a large residue upon distillation. Although specific embodiments of the invention have been described herein, it is not intended to limit the in- ,vention solely thereto, but to include allof the obvious variations and modifications within the spirit and scope of the appended claims.

What is claimed is:

1 1. A complex of tetraisopropyl zirconate with ammonia in which the I mole ratio of ammonia to z irconate is up to 2:1.

' --"2.-A"complex of tetraisopropyl zirconate with ammonia in which the mole'ratio of ammonia to zirconate is uptotlz'l. 3. A complexof tetraisopropyl zirconate with ammo- .IliflKiIlWhiCh the mole ratioof ammonia to 'zirconate is from 0.5:1to121. a 4. Acomplex offtetraisopropyl zirconate with aminonia in whichithe mole ratio of ammonia to zirconate References Cited in the file of this patent Bradley ctaL, J. Chem. Soc. (London) pages 280-285 

1. A COMPLEX OF TETRAISOPROPYL ZIRCONATE WITH AMMOMIA IN WHICH THE MOLE RATIO OF AMMONIA TO ZIRCONATE IS UP TO 2:1. 